From: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
commit 30332eeefec8f83afcea00c360f99ef64b87f220 upstream.
Hardware registers of devices under control of power management cannot
be accessed at all times. If such a device is suspended, register
accesses may lead to undefined behavior, like reading bogus values, or
causing exceptions or system lock-ups.
Extend struct debugfs_regset32 with an optional field to let device
drivers specify the device the registers in the set belong to. This
allows debugfs_show_regset32() to make sure the device is resumed while
its registers are being read.
Signed-off-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
Reviewed-by: Niklas Söderlund <niklas.soderlund@xxxxxxxxxxxx>
Reviewed-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
Signed-off-by: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/debugfs/file.c | 8 ++++++++
include/linux/debugfs.h | 1 +
2 files changed, 9 insertions(+)
--- a/fs/debugfs/file.c
+++ b/fs/debugfs/file.c
@@ -18,6 +18,7 @@
#include <linux/slab.h>
#include <linux/atomic.h>
#include <linux/device.h>
+#include <linux/pm_runtime.h>
#include <linux/poll.h>
#include <linux/security.h>
@@ -1119,7 +1120,14 @@ static int debugfs_show_regset32(struct
{
struct debugfs_regset32 *regset = s->private;
+ if (regset->dev)
+ pm_runtime_get_sync(regset->dev);
+
debugfs_print_regs32(s, regset->regs, regset->nregs, regset->base, "");
+
+ if (regset->dev)
+ pm_runtime_put(regset->dev);
+
return 0;
}
--- a/include/linux/debugfs.h
+++ b/include/linux/debugfs.h
@@ -35,6 +35,7 @@ struct debugfs_regset32 {
const struct debugfs_reg32 *regs;
int nregs;
void __iomem *base;
+ struct device *dev; /* Optional device for Runtime PM */
};
extern struct dentry *arch_debugfs_dir;
